1. Field of the Invention
The present invention relates to a method and an apparatus for production of bio-gas employing a specific technology for improving quality of a raw material fed thereto.
2. Description of the Related Art
In production of bio-gas, organic waste and bio-mass are generally used as main raw materials. However, such main raw materials include a great amount of inhibitory materials (such as ammonia, sulfides, salt, heavy metals, etc.) that deteriorate activity of microorganisms used for producing bio-gas, depending on kinds of the organic waste. These inhibitory materials are mostly present as dissolved matters (in a liquid state) in water, while not existing in a solid portion.
When an organic waste (solid and/or liquid phase) is directly introduced into an anaerobic digestion reactor, inhibitory materials in the liquid-phase of the organic waste deteriorate activity of microorganisms and considerably decrease bio-gas productivity, in turn causing the digestion reactor to be shut-down. In addition, since an organic waste in a solid-phase is fed into the anaerobic digestion reactor, it requires a long residence time in order to decompose the organic waste and causes problems such as increase in a capacity of the digestion reactor and/or equipment costs.
Meanwhile, owing to a slow growth of anaerobic microorganisms, they must reside in an anaerobic digestion reactor for a long term during anaerobic digestion, in order to maintain a desired amount of microorganisms to thereby maximize an amount of bio-gas to be generated. However, a typical anaerobic digestion reactor has a relatively small capacity and does not allow microorganisms to reside therein for a long term, thus not ensuring a desired amount of the microorganisms. As a result, an amount of bio-gas to be generated may be decreased, in turn encountering malfunction or loss of function of the anaerobic digestion reactor.